The inventive subject matter relates to power distribution systems and methods and, more particularly, to power distribution systems and methods using auxiliary contacts for signaling status of circuit interruption devices.
Power distribution systems in industrial facilities, data centers and other applications commonly include at least one automatic transfer switch (ATS) that is configured to switch between alternative power sources, such as a utility source and locally-positioned engine/generator set that serves as a backup in the event of a loss of the utility source.
As illustrated in FIG. 1, a typical ATS installation may include an ATS 120 coupled to a utility source 10a and a local motor/generator set (genset) 10b via respective circuit breakers 110a, 110b. The ATS 120 selectively couples the sources 10a, 10b to a load 20 based on the status of the sources 10a, 10b. ATS 120 may include circuit breakers or contactors therein, respective ones of which are used to couple respective ones of the sources 10a, 10b to the load 20. These breakers or contactors may have auxiliary contacts that are used to sense whether the main circuit breaker or contactor contacts are open or closed. An example of an ATS having such capabilities is the Eaton ATC-900, described in O & M Manual for 40-1200A (480/600 Vac) ATC-900 3-Position, Open/Closed Transition Contactor Based Transfer Switch (2014). It will be appreciated that ATSs may take other forms, e.g., may employ other types of switches.